The goals of this project center on the characterization of spatial vision development in macaque monkeys. These monkeys are an important animal model that can be used for testing hypotheses about the neural basis for the development of vision and its disruption by amblyopia, which is generally defined as a loss of vision due to abnormal visual conditions during development. We have been studying visual development in normal infant monkeys and in monkeys that have experimentally induced amblyopia in order to evaluate theories on the neural limitations on development and the disruption caused by amblyopia. We previously analyzed the performance of strabismic and anisometropic monkeys on various spatial tasks to establish the extent to which their deficits were related to the pattern of contrast sensitivity losses. We have found that in most cases, the pattern of contrast sensitivity loss can account for the loss of spatial precision in amblyopies, and that the patter n of deficits suggests a cortical substrate. We have recorded electrophysiological properties of neurons in primary visual cortex (V1) of amblyopic monkeys, to try to identify the neural basis for the amblyopic deficits. Our results show a strong qualitative correlation between neuronal deficits in V1 cells and behaviorally measured deficits, but the neuronal deficits do not fully acount for the behavioral deficits. We have begun a series of behavioral and physiological studies to identify higher level processing deficits that more fully describe the visual losses in amblyopia. These tasks are based on organization of elements in a visual display into coherent features, an ability called feature integration. We are currently studying the development of this ability. FUNDING NIH grants EY05864 and RR00166. Carandini, M., Movshon, J.A., and Ferster, D. Pattern adaptation and cross-orientation interactions in the primary visual cortex. Neuropharmacology 37 501-511, 1998. Kiorpes, L., Kiper, D.C., O'Keefe, L.P., Cavanaugh, J.R., and Movshon, J.A. Neuronal correlates of amblyopia in the visual cortex of macaque monkeys with experimental strabismus and anisometropia. J. Neurosci. 18 6411-6424, 1998. Kiorpes, L. and Movshon, J.A. Peripheral and central factors limiting the development of contrast sensitivity in macaque monkeys. Vision Res. 38 61-70, 1998. Murphy, K.M., Jones, D.J., Fenstemaker, S.B., Pegado, V.D., Kiorpes, L., and Movshon, J.A. Spacing of cytochrome oxidase blobs in visual cortex of normal and strabismic monkeys. Cerebral Cortex 8 237-244, 1998. O'Keefe, L.P. and Movshon, J.A. Processing of first- and second-order motion signals by neurons in area MT of the macaque monkey. Vis. Neurosci. 15 305-317, 1998. Bair, W., Cavanaugh, J.R., and Movson, J.A. Temporal dynamics of direction selective neurons in areas MT and V1. Soc. Neurosci. Abstr. 24 1745, 1998. Cavanaugh, J.R., Bair, W., and Movshon, J.A. Signals setting contrast gain arise from iso-oriented domains aligned with the receptive field axis of macaque striate cortex neurons. Soc. Neurosci. Abstr. 24 1875, 1998. Kiorpes, L., Tang, C., and Movshon, J.A. Visual efficiency in amblyopic macaque monkeys. Perception (Suppl) 27 21, 1998. Movshon, J.A., Kiper, D.C., O'Keefe, L.P., Cavanaugh, J.R., and Kiorpes, L. Neuronal correlates ofo amblyopia in the visual cortex of macaques with experimental strabismus and anisometropia. Perception (Suppl) 27:16, 1998. O'Keefe, L.P. and Movshon, J.A. The "window of visibility" and direction tuning of STS neurons in alert macaque monkeys. Soc. Neurosci. Abstr. 24 1745, 1998. Priebe, N.J., Bair, W., Cavanaugh, J.R., Movshon, J.A., and Lisberger, S.G. Direction and speed selectivity of gain control in single neurons in macaque visual area MT. Soc. Neurosci. Abstr. 24 648, 1998. Tang, C., Kiorpes, L., and Movshon, J.A. Motion detection in amblyopic macaque monkeys. Invest. Ophthalmol. Vis. Sci. 39 S329, 1998.